There were two Bloody Sundays in Ireland. The first happened in 1920, when an IRA group murdered some British agents because they were ordered to by Michael Colins. The British were pissed, so, they decided to get their revenge by starting a shoot-out at a football match. They killed about 15 Irish Civilians, and in the prisons elsewhere, a couple of IRA members were beaten to death.
The next happened in 1972, when Ireland was split in two, North was held by the British, and south by the Irish (like it is today) and the Irish Catholics in the North were discriminated very heavily, both in public, and in parliament. So, they staged a civil rights march through Derry, which annoyed the British, who murdered a majority of these protestors, all unarmed. This caused a bit of controversey which not a lot of people are happy about to this day.

On 30th January 1972, a vast amount of Roman Catholics in Derry, Northern Ireland, demonstrated a Civil Rights march due to the fact the Catholics were being denied their human rights in most parts of Northern Ireland. The marchers were soon confronted by a blockade of heavily-armed British soldiers who refused to let them continue marching.Lets be realistic here, if you were firstly being denied your Civil Rights, and then prevented from continuing a peaceful march for your rights, you would be more than incensced. So the marchers began throwing sticks and bricks at the soldiers, who were armed with very lethal firearms. Why couldn't they just let them keep on marching? isn't it a bit fascist to deny someone the right to march in favour of their own rights? So then the troops, who knew full-well the effect of their weaponry, opened fire on the marchers, hitting 27 people and killing 13. The troops had lethal weaponry and protective gear on. And they murdered civilians with melee weapons, who were only trying to convince people that they were human beings with rights too.

Don't give me that 'paras are heros' crap. I am half-Irish and some of my family members died in that incident. The military are trained to handle situations professionally, and none of them were injured or killed on that day. Just goes to show that you can't start off something reasonable without some gung-ho arsehole angering you and breaching your rights.

The act that caused the Russian population to turn against the Czar in the early 20th Century. Over 2000 people went to the palace in a peaceful way to ask for more bread from their loving Czar Nicholas II, but the royal guard shot at them, killing between 200 and 1000.